## OUTNANO project starts!

OUTNANO is a Marie Curie Fellowship in the H2020 program funding activity on Out of Equilibrium Nano-photonics

The Marie Curie Fellow is Andrea Marini, a top level young scientist with an extended research career in Nonlinear Photonics.

A new approach for studying novel optical materials in out-of-equilibrium ultrafast dynamics is the goal of this interdisciplinary projects committing together ideas of statical mechanics of complex systems and nonlinear photonics. We will conceive a new generation of nonlinear devices operating at the fastest achievable speeds for classical and quantum applications.

## Complexity in Nonlinear Photonics in Como

School description:

The school brings together experts in emerging photonic technologies and fundamental physics to share with young researchers their knowledge and interdisciplinary approaches for understanding and designing complex photonic systems. The areas covered by the school include: complexity of optical communication systems, in particular topics such as the nonlinear Fourier transform and transmission over multimode fibres, complexity in quantum systems emulated in photonics (including optical computing), PT-symmetric systems, complexity of emerging novel materials and components like meta-surfaces and micro-resonators. Importantly, the complexity in bio-medical photonic applications will be also considered as a high priority topic.

## Quantum Simulation of Rainbow Gravity

Rainbow gravity modifies general relativity by introducing an energy dependent metric, which is expected to have a role in the quantum theory of black holes and in quantum gravity at Planck energy scale. We show that rainbow gravity can be simulated in the laboratory by nonlinear waves in nonlocal media, as those occurring in Bose-condensed gases and nonlinear optics. We reveal that at a classical level, a nonlocal nonlinear Schr\”odinger equation may emulate the curved space time in proximity of a rotating black hole as dictated by the rainbow gravity scenario. We also demonstrate that a fully quantized analysis is possible. By the positive $\mathcal{P}$-representation, we study superradiance and show that the instability of a black-hole and the existence of an event horizon are inhibited by an energy dependent metric. Our results open the way to a number of fascinating experimental tests of quantum gravity theories and quantum field theory in curved manifolds, and also demonstrate that these theories may be novel tools for open problems in nonlinear quantum physics.

The picture below shows spectra and configuration of particles trapped in a quantum simulation of a black-hole.

Braidotti and Conti, in ArXiv:1708.02623

## Topological cascade laser for frequency comb generation in PT-symmetric structures

The cascade of resonant topological structures with PT-symmetry breaking is shown to emit laser light with a frequency-comb spectrum. We consider optically active topological Aubry-Andr\’e-Harper lattices supporting edge-modes at regularly spaced frequencies. When the amplified resonances in the PT-broken regime match the edge modes of the topological gratings, we predict the emission of discrete laser lines. A proper design enables to engineer the spectral features for specific applications. The robustness of the topological protection makes the system very well suited for a novel generation of compact frequency comb emitters for spectroscopy, metrology, and quantum information.

Pilozzi and Conti, arXiv:1707.09191